Electronic detection system



Filed June 1o, 195s ATTORNEY United States Patent u 3,043,588' Patented .lune 26, 1962 3,041,588 ELECTRONC DETECTION SYSTEM .lack Malin, Jamaica, N.Y., assignor to Audiographic, Inc., Bellmore, N.Y., a corporation of New York Filed June 10, 1958, Ser. No. 741,140 Claims. (Cl. 340-213) This invention relates to alarm systems, such as tire and burglar alarm systems, and more particularly to such a system including an inductively coupled transistorized audio oscillator including tone generating means, intermittently and periodically energized when a detector device is tripped.

In accordance with the present invention, a pair of parallel loops are provided and connected to opposite polarity terminals of a source of electric potential. The detector devices, which are, in effect, normally open switches, are connected between these loops at pre-set or predetermined locations. Due to isolating relay means included in the system, the loops may extend relatively great distances, such as two (2) miles or more, without appreciable drain upon the power `supply or potential source even when a detector device is tripped.

Tripping of any detector device picks up a self-latching relay which, when energized, charges a capacitor in shunt with the coil of an interrupter relay. When the condenser is charged a pre-set amount, this interruptor relay is closed to trigger the transistorized audio oscillator to generate a warning tone. As the interruptor relay is closed, it opens the condenser or capacitor charging circuit so that, upon discharge of the condenser, the interruptor relay is dropped or opened to deenergize the oscillator and re-charge the condenser. This action is cyclical- 1y repeated at a rate determined by the constants of the condenser and interruptor relay circuit. The frequency of the generated tone is determined by the constants of the audio oscillator circuit.

A normally closed switch is provided in series with the hold or latching relay to re-set the system after it has been tripped. When this switch is opened, the latching relay is dropped. In order to test the operativeness of the system, the loops are carried through a double pole, double throw switch which, in its normal position, completes the loops and maintains them isolated. In the test position of this switch, the loops are interconnected to energize the tone generator.

For an understanding of the invention principles, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawing. In the drawing, the single FIGURE is a schematic wiring diagram of an alarm system embodying the invention.

Referring to the drawing, a source of electric potential is illustrated, by way of example, as a battery 10 connected to a positive polarity junction point 11 and, in series with a normally closed re-set switch 12 and a fuse 13, to a negative polarity junction point 14. A conductor 16 connects point 14 to a test loop 15 in parallel with a second test loop A conductor 17 connects loop 15 to a junction point 18 which is connected by a conductor 21 to one end of the coil 22 of a latching relay 20. A conductor 23 connects the opposite end of coil 22 to positive polarity junction point 11.

Detector devices 25, which may be thermostatic or other normally open switches, are connected between loops 15, 15 at selected locations along the extent of these loops, which latter may extend for two miles or more. The loops 15, 15 are individually closed and isolated from each other by a test switch 30. A relatively fixed contact arm 31 of switch 30 is connected to one end of loop 15 and normally engaged by a relatively movable contact arm 32 connected to the other end of loop 15. Similarly, the ends of loop 15 are connected respectively to relatively fixed contact arm 31' and relatively movable contact arm 32 which are normally engaged. Arms 32, 32 are conjointly operable by an operator 34 to engage relatively fixed and interconnected contact arms 33, 33'.

Relay 20 has an armature 24 normally disengaged from a contact 26 and connected to conductor 21 and thus to one end of coil or winding 22. A conductor 27 connects contact 26 to negative polarity point 14. Hence, when relay coil 22 is energized, armature 24 engages contact 26 to hold relay 20 closed until such time as re-set switch 12 is opened.

Loop 15 has a negative polarity due to its connection to point 14, and loop 15' has a positive polarity due to its connection to point 11 through relay coil 22. Consequently, when loops 15 and 15 are interconnected either by operation of test switch 30 or operation of detector devices 25, relay coil 22 is energized to engage armature 24 with contact 26 to latch relay 20 and connect conductor 21 to point 14. Test switch 30 may be operated at any time to test the operativeness of the system, whereas devices 25 interconnect the loops only upon occurrence of a condition necessitating an alarm.

When conductor 2l is connected to point 14, a condenser 35 is charged over the following circuit: point 11, conductor 23, condenser 35, conductor 36, contact 42 of a relay 40, armature 41, conductor 43, conductor 21, armature 24, contact 26, conductor 27 and point 14. When capacitor or condenser 35 is charged to a predetermined arount, it discharges through coil `44 of relay 40 to energize this coil.

Armature 41 is engaged with contact 46 to energize the audio oscillator including transformer 45 and power transistor 50. Transformer 45 has two windings, 47 and 48. Transistor 50 has a base 51, collector 52, and emitter 53. `A conductor 54 connects one end of winding 47 to conductor 21. The other end of winding 47 is connected by a conductor 56 and a biasing resistor 57 to base 51 of transistor 50. A conductor 58 connects relay contact 46 to loud speaker 55, and a bias resistor `61 connects conductor 58 to one end of winding 43. The other end of winding 48 is connected to a conductor 62 interconnecting collector 524and speaker 55. A ballast resistor 60, replaceable by a loud speaker, is connected in conductor 62. A conductor 63 connects emitter 53 to point 11, and is connected by a bias resistor 64 to base 51. A pilot lamp 65 is connected between relay contact 46 and conductor 23 in series with a resistance 66.

Relay 40 remains closed while capacitor 35 is discharging, and then drops to re-engage armature 41 with contact 42. When armature I4l. is engaged with contact 46, the tone generating transistorized audio oscillator, which is inductively coupled, is energized to generate a tone at a frequency of, for example, 700 c.p.s. The frequency may be changed to another gure by proper selection of resistances 57, 61 and 64. When armature 41 is re-engaged with contact 46, condenser 35 is re-charged. The frequency of the intermittent operation of relay 40 is determined by the values of capacitor 35 and resistance 66. Re-setting of the System is effected by momentarily opening re-set switch 12 to drop relay 30.

The frequency of operation of cyclic relay 40 is controlled by the value of condenser 35 and the resistance of relay coil 44, as well as by the combined values of the potential source and other circuit resistances. As the potential of battery 101 drops, the frequency of operation of relay 40 will tend to increase and the audio oscillator frequency will decrease. The speaker coils or magnets, acting as additional inductance in the audio oscillator circuit, also aiect its frequency.

3 Test switch 34), when in the test position, breaks theV continuity of loops 1S, 15 and tests the entire length of both loops'by shorting the extreme ends of the loops.

- This will test the continuity of the loop as, if a loop or 15 is broken, the system will not operate inthe test` position of switch 30 thus indicating a fault. A discontinuity orV break in either loop will not disable the alarm system, which will still function through any element 25.

However, a fault shown in the test position of `switch 30 indicates the need for repair of either or both loops.

Light 65 and resistance 66 have values such that, when switch 30 is in the test position, a dim light shows the need for recharging or replacing battery 10, and a brightV light indicates good condition of the battery.

Relays 2t) andV 40; isolate the oscillator from loops 15,

` 15k so that the oscillator energy is not fed to the loops. Y This enables the use of very longVV loops.

bination, an audio oscillator arranged, when connected to a source of electric potential, to generate audio pulses at a pre-set frequency; a source of electric potential; a first relay operable, when energized, to connect said oscillator to said source; a self-latching relay connected to said source; a detection circuit, including at least one normally open detector switch, connected across said Source, said detector switch controlling energization of said latching relay; and means effective responsive to energization of said latching relay to periodically energize said first relay; said latching relay, when energized, con necting both Vsides of said detection circuit to the same terminal of said source to isolate said oscillator from said detection circuit to prevent feeding of oscillator energyA to Asaid detection circuit.

2. An electronic detection circuita's claimed in claim 1 in which said detection circuit comprises a pair of relatively relongated loops respectively connected to one terminal of said source and to saidV latching Vrelay; and plural normally open detector switches connected between said'loops; said latching relay, when energized, connecting both loops to said one'terminal of said source, to isolate said loops fromrsaid audio oscillator.

3. An electronic detection system comprising, in combination, an audio oscillator arranged, when connected to a source of electric potential, to generate audio pulses at a pre-set frequency; a source of electric potetial; a first relay operable, when energized, to connect said oscillator to said source; a self-latching Vrelay connected to said source; a detection circuit, .including at least one normally opendetector switch, connectedacross said source, said detector switch controlling energization of said latching relay; anda capacitance connectedin charging relaticrn` to said source when saidv latching relay is energized and said rst relay is deenergized and effective, when charged, to energize said first relay; said first relay, when energized, opening the charging circuit ofsaid capacitance; whereby said first relay is periodically energized during energization of said latching relay; said latching relay, when energized,'connecting both sides of said detection circuit to the same terminal of said source to isolate said oscillator from said detection circuit to prevent feeding of.. oscillator energy to said detection circuit.

p 4. -An electronic detection system comprising, in cornbination, an audio oscillator including'a transistor triode arranged, whenrconnected to a source of electric potential, to generate audioV pulses at a pre-set frequency; a source of electric potential; a first relay operable, when energized, to connect said oscillator to said source; a self latching relay connected to one terminal, of Said source; a detection circuit, including at least one normally open detector switch, connected between the other terminal of said source and said latching relay, said detector switch controlling energization of said latching relay; and a capacitance connected ink charging relation to said source when said latching relay is energized and said first relay is deenergized and effective, when charged, to energize said first relay; said first relay, when energized, opening the charging circuit of said capacitance; whereby said first relay is periodically energized during energization of saidrlatching relay; said latching relay, when energized, connecting both sides ofv said detection circuit directly to said other terminal of said source.

5. An` electronic detection system comprising, in com bination, an inductively coupled audio oscillator including a transistor triode arranged, when connected to a source of electric potential, to generate audio pulses at a pre-set frequency; a source of electric potential; Va first relay operable, when energized-,to connect said oscillator to saidV source; a self-latching Vrelay connected to one terminal of said source; aV detection circuit, Vincluding at least one normally open detector switch, connected between the other terminal of said'source and said latching relay, said detector switch controlling energization of said latching relay; and a capacitance connected in charging relation to said source when said latching relay is energized and said rst'relay is deenergized and effective, when charged,

to energize said first relay; said first relay, when energized',V opening the charging circuit of said capacitance;

whereby said first relay is periodically energized duringV energization of said latching relay; said latching relay, when energized, connecting both sides of said detection circuit directly to saidV other terminal of said source.

6. An electronic detection circuit as claimed in claim 5 in which said detection circuit comprises a pair of relatively elongated 'loopsrespectively connected toV one terminal of said source and to said latching relay; and plural normally open detector switches connected between said loops; said latching relay, when energized, connect-V ing both loopsy to said one terminal of said source, to isolate said loops from said audio oscillator.

7. An'electronicidet'ection circuit as claimed in claim 6 including a double-pole,- double-throw test switch connected'inl theV respective loops and manually operable to interconnect the loops.

8. An electronic detection Vcircuit as claimed in claim 5 including a normally closed manually openable switch in the latching circuit of said latching relay.

9; An electronic detection system comprising, in combination, a signal generator; a source of electric potential; apair of elongated detection loops extending, in parallel circuit relation, from respective ends adjacent said generator and said source; at least one detection switch connected between said" loops and adapted, when actuated, to interconnect said loops; means connectin-gone loop to one terminal of said source and the other loop to the other Vterminal of said source in series with 1n-electrically op- References Cited in the file of this patent UNITED STATES PATENTS Reagan Nov. ll, 1941 2,448,026 Grant Aug. 3l, 1948 2,473,683 HinesV June 2l, 1949 V2,647,252 Moore July 28, 1953 

